Lynas must export by-product created by operations at the Malaysian plant or risk having its operating license revoked, four Malaysian ministers said on Monday.

The license remains issued and valid, and there is no legal impediment to Lynas carrying out its operations at the plant, the company said in a stock exchange filing.

Lynas will ensure all residue material is converted into co-products and exported from Malaysia if the co-products are not approved for use in Malaysia as per the terms of its operating license, the company said.

Lynas' Executive Chairman Nick Curtis told reporters the company had received "significant commercial interest" from potential buyers of the by-product or residue, which emits naturally occurring, low-level radiation.

"But we need to produce it before we can commercialize it," Curtis said.

Lynas has been embroiled in lengthy environmental and safety disputes with local residents since construction began two years ago. Its $800 million plant, which opponents say is environmentally hazardous, began operations late last month after long delays caused by legal challenges and safety disputes.

Located in the east coast city of Kuantan, it had been ready to fire up since May.

The Malaysian high court will hear an application for judicial reviews to block operations of the plant on February 5 next year.

Lynas shares, which last traded at A$0.605, were placed in a trading halt on Tuesday, having traded as high as A$1.63 in February.